I got into this game by producing music for theater, which might be a little different from the intent of this thread...?? But that's the first time I heard my "work" in public: in a theater full of about 500 people.
It was kind of nerve-racking, because in a theater, it's a captive audience. And the first time was in my home town, in a theater full of mostly people who live in or near my hometown; plus all the local major and indie print media were there to document the proceedings.
So it kind of felt like my balls were on the chopping block, in advance. I wasn't "pleasantly surprised" by the first time I heard my "work" in public, because I saw it coming ahead of time.
I remember asking my parents and my girlfriend to stay away from the opening night. Because if I was going to get slaughtered, I would rather they not witness that.
It went well though. My piece got a standing ovation, and the artistic director dragged me onstage at the end to take a bow with the company. Great reviews in the press. ASCAP Composer award. Happy ending, blah blah blah.
Mind you, this was after a decade of playing in bands, floundering in the club scene, and shopping a bazillion band demos, with absolutely nothing to show for that.
Keep plugging away at this racket, and you never know what's going to pop up on the cultural radar, or when, or where. Just enjoy it if/when it does eventually happen. Soak it up for all it's worth, baby, because we all know life is full of hardship and pain. Take that moment of joy and savor it down to the last drop, because that's why we do this.